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<html>

<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel="stylesheet" href="../bootstrap-5.1.3-dist/css/bootstrap.css">
    <script src="../bootstrap-5.1.3-dist/js/bootstrap.js"></script>
</head>

<body class="container">
    <h3 class="mb-4">列包装</h3>
    <div class="row">
        <div class="col-9 py-3 border bg-light">.col-9</div>
        <div class="col-4 py-3 border bg-light">.col-4<br>因为9 + 4 = 13 >12，4列宽的div被包装到一个新行上，作为一个连续的单元。</div>
        <div class="col-6 py-3 border bg-light">.col-6<br>后续的列沿着新行继续排列。</div>
    </div>
</body>

</html>